The present invention relates to an apparatus which presses the end of a tube to reduce dimension thereof to form what is called a point or more specifically the invention relates to a novel apparatus for reducing a diameter or pointing a tubular workpiece so that the same may be easily inserted into a die for drawing the tube and reduce its diameter.
In the prior art there is known a number of apparatuses which will reduce the diameter of tubing. Basically, the devices employ jaws which reciprocate radially inward, for example, as seen in my prior U.S. Pat. No. 3,154,978. Other approaches which utilize modified jaws but which operate on a similar principle are seen in the Valente patents U.S. Pat. Nos. 3,245,247 and 3,417,598. Still other forms of jaws are seen in the Schuetz U.S. Pat. No. 3,370,451. In each of these disclosures, a tube is positioned into an opening and jaws collapse the tube to the desired shape. With these and other similar tube pointers, while they are capable of producing usable points, they are subject to jamming. For example, in my prior United States Patent referenced above, the fin surface of the jaw grips the tube and prevents the tube from elongating which causes the pointer to jam. In addition, utilizing a jaw such as I have previously disclosed, there is the possibility of metal chips being generated due to the openings in the jaw surfaces. Also with certain types of jaws it is almost impossible to work on stiffer metals such as brass, for the parts of the jaws will break. Further in many types of prior art devices particularly in devices as seen in the Schuetz patent U.S. Pat. No. 3,370,451, the metal of tube while it is being compressed would tend to extrude into any opening that it can find, and this is well illustrated in FIG. 11 of this particular patent. The result is various point sizes that may not be easily predicted, it being necessary to provide a point with a predictable size so that it can be grasped by the drawing gripper jaws.